3n 



easily cut aspens, they would have greatly reduced 

 the available food-supply. It would have required 

 most of these aspens to build the dam. The only 

 conclusion I can reach is that the beavers not 

 only had the forethought to begin work to obtain 

 a food-supply that would be needed two years 

 after, but also, at the expense of much labor, 

 actually saved the scanty near-by food-supply of 

 aspens by making their dam with the hard, fire- 

 killed trees. 



A large harvest of aspen and willow was 

 gathered for winter. Daily visits to the scene of 

 the harvest enabled me to understand many 

 of the methods and much of the work that other- 

 wise would have gone on unknown to me. Early 

 in the harvest an aspen cluster far downstream 

 was cut. Every tree in this cluster and every 

 near-by aspen was felled, dragged to the brook, 

 and in this, with wrestling, pushing, and pulling, 

 taken upstream through shallow water, for most 

 mountain streams are low during the autumn. 

 In the midst of this work the entrance or inlet 

 of the canal was blocked and the bow dam was 

 cut. The water in the brook was almost doubled 



148 



